> Like this site, one of the highest signal to noise ratios on the internet because no one has any incentive to game it.

There's tons of incentive to game it. If it wasn't, why would all kinds of startups and tech companies have alert bots and slack channels implemented to allow their employees to swoop in and participate in HN threads that are relevant to their marketing interests?

IIRC, the one's who've come clean about doing that have been fairly scrupulous about, but I'm sure they're just the tip of the iceberg.